Virtual reality system for treating patients with anxiety disorders

ABSTRACT

A virtual reality system provides effective exposure treatment for psychiatric patients suffering from a particular anxiety disorder. The system is characterized by a video screen disposed in front of the patient to display an image of a specific graphical environment that is intended to trigger anxiety within the patient as a result of the particular patient phobia. A headset is worn by the patient, and has sensors disposed to detect movement and positioning of the patient&#39;s head. A computer program controls the operation of the system, and is designed to control the display of the graphical environment on the video screen, monitor the headset sensors and determine the position of the patient&#39;s head, and controllably manipulate the graphical environment displayed on the video screen to reflect the movement and position of the patient&#39;s head. In a preferred embodiment, a sensor is provided to automatically detect a level of patient anxiety, and the computer program is designed to monitor this sensor and controllably manipulate the graphical environment displayed on the video screen in response thereto. In other embodiments, sound and tactile feedback are provided to further enhance the graphic emulation.

CROSS REFERENCE TO RELATED APPLICATION

This application is a Continuation-In-Part of U.S. patent applicationSer. No. 08/622,756 filed Mar. 27, 1996, U.S. Pat. No. 5,807,114.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to psychiatric treatment ofpatients with phobias, and more particularly to a system for providingexposure therapy for psychiatric treatment of patients having variousphobias.

2. Discussion of the Related Art

As is well known, people from all walks of life are known to suffer froma wide variety of phobias or related anxiety disorders. Simply defined,a phobia is an irrational fear of an object, activity, or situation thatleads to a compelling desire to avoid it--e.g., fear of heights. Notonly are there a wide variety of phobias, but any given type maymanifest itself differently, or to a different degree, in differentpersons. Therefore, treatment programs are generally tailoredindividually to specific patients. Nevertheless, certain generalities inregard to treatment programs can be made.

Namely, exposure theory espouses the view that patients suffering from aparticular phobia can be treated to successfully manage that phobia byrepeated exposure to the particular situation. For example, patientssuffering from acrophobia (fear of heights) may be treated by exposureto high places. Elevators, balconies, building windows, bridges, andairplanes are environments where a patient being treated for acrophobiamay be deployed. Although the degree of success varies from patient topatient, exposure therapy has been proven effective in many cases andcontrolled studies.

A more particular derivation of exposure therapy is referred to as"graded exposure therapy", whereby a patient is exposed to particularsituations in gradations of gradual but increasing severity. Forexample, an acrophobic patient may be treated by leading the person to afirst floor balcony. While the initial deployment may result inrelatively high levels of anxiety, it has been found that the anxietylevel will typically subside after a patient has spent some period oftime in the environment. Therefore, after the patient has spent sometime on the first floor balcony, and has reached some level of comfortin that position, he may then be led to a second floor balcony, and soon. In this way, the patient may be continually moved to higher andhigher elevations, allowing the anxiety level to subside at each levelbefore continuing. Repeated sessions of treatment in this manner (i.e.,graded exposure) have been found to successfully help patients in facingand managing phobias. It is, moreover, desired to vary the treatmentenvironment. In one session, a patient may be gradually led tosuccessive balcony floors as described above. In a subsequent session,that same patient may be led up multiple flights of stairs, elevated upseveral floors in an elevator, or exposed to some other environment.

Typically, there are two categories or methods by which exposure therapyis practiced in vivo and imaginal. Pursuant to the in vivo (i.e., "reallife") approach, patients are exposed to real situations and stimuli. Incontrast, the imaginal method is practiced by having patients imagineparticular situations or scenarios. For example, in a treatment methodknown as systematic desensitization, a patient is instructed to relax,then imagine a stimuli for a situation that causes anxiety, relax again,then stop imagining. These steps are repeated and as the levels ofpatient anxiety begin to subside, the patient is asked to imagine adifferent scenario that provokes higher levels of anxiety.

While both in vivo and imaginal therapy has proven effective fortreating different patients, both are characterized by variousshortcomings. Notably, in vivo treatment is typically time consuming andtherefore costly. In this approach, the patient must be taken from thetherapist's office and deployed in real life settings, which excessivelyconsumes the therapist's time and is therefore costly. In addition,subjecting the patient to situations outside the office (e.g., publicplaces) compromises the doctor patient confidentiality and may beembarrassing for the patient. As a result, many patients are unwillingto undergo such therapy and go untreated. Moreover, in certain treatmentenvironments such as an elevator or an airplane, the environment is notunder patient or therapist control, often resulting in excessive levelsof anxiety on the part of the patient, which may be counter-productivefor the therapy.

Likewise, the imaginal method of treatment suffers from shortcomings ofits own. Most notably, this method has proven to be largely ineffectivefor patients with very poor imaginations. Like the in vivo method, theimaginal method is often time consuming and expensive, as it may takeexcessive amounts of time for the patients to imagine scenarios toadequately invoke episodes of anxiety for proper treatment. In addition,patients may find it often difficult to sustain the imagined scenarioonce high levels of anxiety have set in.

Although the specific examples set forth above detail scenarios andenvironments for treating acrophobic patients, it is appreciated thatexposure therapy has been widely used in a variety of phobias andanxiety disorders.

SUMMARY OF THE INVENTION

Accordingly, a primary object of the present invention is to provide animproved system and method for treating patients using exposure therapy.

A more specific object of the present invention is to provide a systemfor effecting exposure therapy on patients within the confines of adoctor's office.

Another object of the present invention is to provide a system foreffecting exposure therapy in a timely and therefore cost-effectivemanner.

Additional objects, advantages and other novel features of the inventionwill be set forth in part in the description that follows and in partwill become apparent to those skilled in the art upon examination of thefollowing or may be learned with the practice of the invention. Theobjects and advantages of the invention may be realized and obtained bymeans of the instrumentalities and combinations particularly pointed outin the appended claims.

To achieve the foregoing and other objects, the present invention isgenerally directed to a virtual reality system for treating patientswith a particular anxiety disorder. Principally, the system includes avideo screen for displaying a graphical environment, a headset worn bythe patient and having sensors disposed to detect movement andpositioning of the patient's head, and a computer program forcontrolling the operation of the system. More particularly, the computerprogram controls the graphical display on the video screen, so as topresent a particular graphical environment that is targeted for aparticular patient feared stimulus to elicit responsive anxiety fromthat patient. As is known in virtual reality systems, the computerprogram monitors the sensors associated with the headset to determinethe position and movement of the patient's head. In response, theprogram controls the graphical display on the video screen accordingly.

In accordance with one aspect of the present invention, means areprovided for sensing or detecting patient anxiety. This feature may beprovided by a sensor that monitors the patients pulse rate oralternatively blood pressure, whereby increasing pulse rate or bloodpressure indicates increasing levels of anxiety. Alternatively, anelectrodermal (or galvanic skin response) sensor may be provided tomonitor perspiration levels of the patient, whereby increasedperspiration indicates increased anxiety. In yet another embodiment, thetherapist may monitor the patient's anxiety, either by observing visibleindications, or by talking with the patient and being told when thepatient is uncomfortably anxious using the Subjective Units ofDiscomfort (SUDS) anxiety scale. A separate video screen may be providedfor the therapist to monitor, so that the therapist can better controlthe emulated environment. For example, one virtual environment presentsan elevator for treating acrophobic patients. By visually monitoring thegraphical environment presented to the patient, the therapist can bettercontrol the movement and height of the "virtual" elevator, using thepatient's anxiety level to guide the height of the elevator.

In accordance with another aspect of invention, tactile feedback isprovided to further enhance the "virtual" environment. In this regard,physical objects may be statically displayed within the reach of thepatient, that correspond in placement with visible objects displayed onthe video screen. Patients may, therefore, touch objects that aredisplayed in the image to further enhance the effect of the virtualscene. Alternatively, sound or vibratory feedback may be provided. Inone embodiment of the present invention, the interior of an aircraft,including a view from a window, is graphically displayed on the videoscreen for treating patients who have a fear of flying. Soundcorresponding to aircraft engine noise may be provided to enhance thevisible scene. In addition, the patient may view this scene from aseated position to emulate a seat on the aircraft. The seat may,correspondingly, be vibrated in accordance with sound vibrations andgraphic perturbations (indicative of the aircraft having a bumpy ride).This too reinforces the virtual environment presented to the patient,and enhances the results of the therapy session.

In accordance with a related aspect of the present invention, the soundgenerated and directed to the patient may be controllably affected bymovement of the patient's head. Just as the computer program is designedto monitor a headset worn by the patient to controllably manipulate thegraphical image displayed on the video screen, the program may likewisecontrol the presentation of sound to the patient. Therefore, not onlywill the sound be varied in a corresponding relation to the changingscene displayed on the video screen, but it may also be varied (involume and direction) in accordance with movement of the patient's head.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings incorporated in and forming a part of thespecification, illustrate several aspects of the present invention, andtogether with the description serve to explain the principles of theinvention. In the drawings:

FIG. 1 is a block diagram illustrating the principal hardware andsoftware components in a virtual reality system;

FIG. 2 is a block diagram depicting the interrelation of the principalhardware and software components of a virtual reality system utilized inconnection with the present invention;

FIG. 3 is a software flowchart illustrating the top-level operation ofthe present invention;

FIG. 4 is a block diagram illustrating the principal hardware componentsof an embodiment constructed in accordance with one aspect of thepresent invention;

FIG. 5 is a software flowchart illustrating the operation of anembodiment constructed in accordance with one aspect of the presentinvention;

FIG. 6 is a software flowchart illustrating the operation of anembodiment constructed in accordance with one aspect of the presentinvention;

FIG. 7 is a state diagram illustrating the operation of an embodimentconstructed in accordance with one aspect of the present invention;

FIGS. 8A-8D are facsimiles of screen displays illustrating a virtualembodiment of one embodiment of the present invention;

FIG. 9 is a facsimile of a screen display illustrating a virtualembodiment of one embodiment of the present invention;

FIG. 10 is a facsimile of a screen display illustrating a virtualembodiment of one embodiment of the present invention;

FIG. 11 is a block diagram illustrating the principal hardwarecomponents of an embodiment constructed in accordance with one aspect ofthe present invention;

FIG. 12 is a software flowchart illustrating the operation of anembodiment constructed in accordance with one aspect of the presentinvention;

FIG. 13 is a state diagram illustrating the operation of an embodimentconstructed in accordance with one aspect of the present invention;

FIG. 14 is a facsimile of a screen display illustrating the interiorcabin space of a passenger airplane;

FIG. 15 is a facsimile of a screen display illustrating an airborne viewof an airport; and

FIG. 16 is a facsimile of a screen display illustrating a view out of apassenger window of an aircraft.

Reference will now be made in detail to the description of the inventionas illustrated in the drawings. While the invention will be described inconnection with these drawings, there is no intent to limit it to theembodiment or embodiments disclosed therein. On the contrary, the intentis to cover all alternatives, modifications and equivalents includedwithin the spirit and scope of the invention as defined by the appendedclaims.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Turning now to the drawings, FIG. 1 illustrates the principal componentsin a virtual reality system depicting the separation between hardwareand software. As will be described in further detail below, the primaryaim of the present invention is to provide an effective means fortreating a variety of patients suffering from anxiety disorders ofvarious kinds. Because virtual reality systems respond to patientmovements to create a sense of presence or "immersion" within thevirtual environment, applicants have found that such systems provide aneffective vehicle for achieving the concepts of the present invention.

As is known, virtual reality systems operably combine hardware andsoftware in real-time fashion. A central hardware component in almostany virtual system is the headgear 20. Various types of headgear areknown. For example, a headgear, such as that illustrated in the figure,has only a single video screen 22 for displaying an image of a virtualenvironment immediately before the user's eyes. The screen 22 may beflat or, alternatively, curved, either physically or optically, toextend to each side of the eyes and effectively cover much of the user'speripheral vision. Alternatively, stereo goggles may be utilized.Headgear of this type provide two display screens--one immediately infront of each eye. As is known, the images displayed on each screen areslightly offset, so as to provide the appropriate sense of depthperception for objects displayed on the screens.

Speakers 24 may be also be provided in the headset 20. Like the videoimages displayed on the screen 22, sound may be similarly provided tosupport the virtual environment illustrated on the video screen. Asmentioned, an important feature in a virtual reality system is toprovide the user with a sense of presence within the virtualenvironment. To this end, sensors 25 are provided in connection with theheadgear 20 to monitor the position and movement of a user's head. Asthe user moves his head, the image displayed on the video screen 22 isadjusted accordingly. Similarly, the volume of the sound emitted onspeakers 24 may be accordingly adjusted. That is, in the virtualenvironment, the sound source may be assigned a location. As the usermoves his head, the sound volume may be slightly varied between the twospeakers to coincide with the alignment of the user's ears with thesound source.

Another hardware component frequently used in a virtual reality systemis a device, usually resembling a glove, that is worn on the user'shand. The device is equipped with numerous position and bend sensors toclosely monitor finger and hand movements. All such devices will behereinafter referred to as "sensor-gloves" 30. This device is worn on auser's hand like any normal glove. It is equipped, however, withnumerous sensors to monitor the position and movement of the user's handand fingers, and provides an effective means for allowing the user topositively engage the virtual reality environment as more than a mereobserver. It will be appreciated that the visual and audio sensoryperceptions provided in connection with the headgear 20 may effectivelyimmerse the user in the virtual environment, as an observer, othermechanisms are required in order to allow the user to interact withinthe virtual environment. The sensor-glove 30 provides this mechanism.

For example, one of the virtual environments that will be discussed inconnection with the present invention, is an elevator used for treatingpatients with acrophobia (fear of heights). The elevator includescontrol buttons to allow the user (patient) to instruct the elevator togo up, go down, or stop. These control buttons are visually presented tothe user on the display screen of the headgear. They are not physicallyreal, but exist only visually in the virtual environment. The user,nevertheless, is able to interact with that environment and depress thebuttons by using a sensor-glove 30, or other similar input means. As theuser moves his hand, the system tracks that movement and incorporates animage of the hand into the virtual environment display. Just as in a"real-world" manner, the user may utilize the visual feedback of thedisplay showing the position of a hand in relation to the controlbuttons to move his hand to align the virtual hand with the controlbuttons.

Another component, denoted as "other" 32, is provided to illustrate thatmany other hardware components are known for using virtual realitysystems, and may be utilized in connection with the present invention.For example, rather than a video screen 22, provided in a headset 20, analternative video screen may be provided, such as a CRT positioned infront of the patient. A variety of other input means, other than thesensor-glove 30, are known as well. In this regard, the user may utilizea flight stick, a tracker, a mouse, etc. as a means of providingpositive input and interaction with the virtual environment. Indeed,experimentation is presently ongoing in the development of a body suitwith numerous sensors to track the movements of a user's entire body,much like the sensor-glove 30 tracks the movements of a user's hand andfingers. An exhaustive description of these devices, however, will notbe provided herein, as they will be understood by persons skilled in theart and do not form a part of the present invention.

In conjunction with the various hardware components, software providesthe remainder of the virtual environment. In this regard, there arecompanion processing and interface modules to interact with eachhardware component previously described. For example, a video processingmodule 40 outputs to the display screen 22 the appropriate videoinformation for display to the user. It will be appreciated that thisvideo information reflects not only the environment, but also theposition of the user's head as detected by sensors 25 and the positionof the user's hand as detected by sensor-glove 30. Similarly, an audioprocessing module 42 provides similar control over the sound emitted bythe speaker 24. Thus, the blocks denoted as "tracking" 41 and "videoprocessing" 42 provide the appropriate input/output interface with thecorresponding hardware components. At the same time, these blocksinterface (via software) with the virtual (object) environment tointegrate the user (via hardware) into the virtual environment.

In regard to the graphical or virtual environment provided by the systemand as is known, such virtual reality systems utilize object-orientedprogramming techniques to effectively provide the virtual environment.In this regard, an object can represent anything that can be named, fromsomething as abstract as degrees of volatility, to something as concreteas a physical object. In addition, objects or parts of programs caninherit features from other objects, or from pre-coded generic examples.In this regard, it may be necessary only to note that one object isidentical to another except for a certain feature or features, and thento define the differences.

After designing the various objects that will be used in a given virtualenvironment, object characteristics must also be defined. Thesecharacteristics contain rules of behavior that define how a certainobject will act or appear in a given environment. For example, ballsbounce in response to gravity and elasticity, water flows at a raterelating to both the depth of the water and the inclination or gradedown which the water flows. These dynamics are expressed throughalgorithms in the software.

In many instances, the definition of particular objects and theirassociate dynamics is hardware or machine specific. In order tofacilitate not only the definition of objects, but also portabilityamong different systems, a variety of commercially-available virtualreality development toolkits have been provided. The identification anddescription, however, of particular toolkits or other developmentsoftware is not provided herein, as it is not deemed necessary in orderto practice the present invention. Indeed, those skilled in the art willappreciate a variety of development tools for implementing the conceptsand teachings of the present invention.

In keeping with the description of the object-oriented software, objecttrees are utilized in combining or defining related objects. Forexample, a table may consist of a table top and 4 legs, each of whichmay be expressed as a separate object. Since each of the 4 table legs isfixed in relation to the table top, a logical relation (fixed) isdefined among the five objects. This may be expressed in terms ofparent-child objects, wherein the table top is a parent object, and eachleg is a child object of the parent. As is know, this may be graphicallyexpressed in terms of an object tree. In one embodiment, therelationship between a parent object and a child object is one oflocation, orientation, and scale. Another way to express thisrelationship is to say that a child's position is defined in terms ofits parents coordinate system, which is in turn defined as its positionin relationship to its parent's coordinate system, and so on. Allobjects in a tree have a position that is ultimately defined in terms ofthe coordinate system of the top-most object, or root node. Utilizingobject trees, movement of a root node object may be calculatedindependently, and the movement of all other objects within the tree maybe calculated based upon the movement of the root object. As is known,this simplifies the calculations required in displaying a given virtualenvironment.

As is known, an object's position may be represented internally as a 4×4matrix which is a composite of a translation, a rotation, and a scaletransformation. This matrix may be used to determine the position ofeach point in an object's geometry, in relation to the object's parent.The translation component determines where a point at an object's originwill be from the parent object. The rotation and scale componentsdetermine where the points away from the origin will be in relationshipto that origin. It is significant to note that the rotation component isa rotation around the parent object's origin, rather than the object'sorigin and it is also important to note the changes in position of aparent object cause position changes in its child objects as well. Toillustrate this point, and in keeping with the example of the table topand four legs, if the table top is rotated., then the legs will rotateabout the origin of the table top, as opposed to their individualcomponent origins.

Objects have a geometric appearance which are preferably designed bypolyhedron, polyline, text and light sources. This geometry may be readfrom an object description file, or may be generated dynamically. Ageometry may be defined as a list of primitives, each of which may be apolyhedron, a textured polyhedron, a polyline, text, or a light source.A polyhedron primitive is simply a collection of polygon faces which alluse a subset of a list of vertices and normals. A textured polyhedron isa special polyhedron which contains texture vertices information used tomap textures to the polygon faces. A polyline primitive is a collectionof continuous lines which all use a subset of a list of vertices. A textprimitive may be a multi-line block of text which has a location,orientation, and scale in relationship to the object it is a part of.The light source primitive is a light definition. Each visible primitivecan have a highlighted material associated with it which, if nohighlight geometry is specified, will override the primitive's usualmaterial when the object is being highlighted.

Having described a generic virtual reality environment for the presentinvention, reference is now made to FIG. 2, which more specificallyillustrates the interrelation of components in a virtual reality systemimplementing the present invention. In addition to hardware andsoftware, a patient 50 and therapist 51 are also included. Single-endedarrow 52 illustrates the patient interaction with position trackers 55,which may include sensors on the head gear as well as sensors in thesensor-glove 30. This position and sensor data is then input to acomputer 56 which controls monitors (video displays) and speakers 58, aswell as the head-mounted display 60. The head-mounted display 60, asillustrated by the single-ended arrow 61 provides visual and audio inputto the patient 50.

Double-ended arrow 62 reflects bi-directional interaction andcommunication between the patient 50 and therapist 5 1. In oneembodiment, the therapist 51 may, through a series of questions,ascertain the patient's level of anxiety. A computer operator 65 mayalso be present to provide direct input into the computer 56. Thecomputer operator 65 may be an individual dedicated to control theoperation of the computer 56 or, alternatively, may be a therapist withsufficient working knowledge of the computer system to control certaininput parameters. For example, and as previously mentioned, oneenvironment of the present invention emulates an elevator for treatingpatients with a fear of heights. The therapist 51 detects increasing ordecreasing, levels of anxiety within the patient 50. Thereafter, thetherapist 51, via computer operator, 65 may control the computer 56 todecrease or increase the elevation of the elevator.

Arrows 70 indicate the general interaction between hardware andsoftware. The software is represented in three principle blocks ormodels: the virtual reality toolkit 71, the visual model 72 and theapplication program 73. The visual model has the name it implies,defines or depicts the environment for a particular virtual application.The application program receives the visual model and interacts with thevirtual reality toolkit so as to define user interaction with the visualmodel. The operation and interaction of these software modules will beappreciated by those skilled in the art.

Turning now to the broad features of the invention, reference is made toFIG. 3, which shows a software flowchart illustrating the principalsteps in the present invention. Broadly, the present invention exposes apatient with a particular anxiety disorder to a virtual environmentemulating an environment or event targeted to elicit an increase inpatient anxiety, associated with a particular anxiety disorder. Forexample, in patients having a fear of heights, various virtualenvironments including an elevator, a balcony, and a walking bridge havebeen designed to elicit patient anxiety. The system operates to vary theintensity of the virtual environment in response to changing levels ofpatient anxiety. In a treatment method known as graded exposure, apatient is exposed to a particular stimulus that elicits an increasedanxiety. After a period of time, with continued exposure, the patientanxiety begins to subside. In response, the system operates to change orintensify the virtual environment in order to again increase patientanxiety. This process is repeated through several gradations as a way ofefficiently exposing patients to feared environments or stimuli.

More specifically, the operation of the present invention begins bydetecting or otherwise receiving an initial patient anxiety level (Step100) and setting an initial exposure level or rate accordingly. In thisregard, rather than beginning at some default exposure level or rate, apreferred embodiment of the invention recognizes that patients' anxietylevels may be different at the onset. For example, on an initial therapyvisit, a first patient may be innately more apprehensive than, forexample, a second patient. Similarly, the first patient may have acertain level of anxiety or apprehension on his or her first visit withthe therapist, and a lower level of anxiety or apprehension whenbeginning a treatment session on a subsequent visit to the therapist. Inthese scenarios, the illustrated embodiment accounts for such variationsand sets an initial exposure rate or level accordingly.

As previously mentioned, the system may detect or receive the initialpatient anxiety level by data input manually by a therapist and/orcomputer operator. Alternatively, a sensor may automatically detect alevel of patient anxiety. The sensor may be in the form of a device thatmonitors the patient's pulse rate, blood pressure, or epidermalmoisture.

The illustrated embodiment of FIG. 3 also differentiates betweenexposure level and exposure rate. One or the other may be appropriatefor any particular embodiment. In the elevator example previouslymentioned, the illustrated embodiment may set the initial exposure levelof, for example, the third floor. In this instance, the elevator wouldascend to a third floor level and stop. It would remain stopped untilthe patient anxiety subsided to a level sufficient to permit furtherelevation of the elevator. Alternatively, the illustrated embodiment maybe configured to elevate the elevator at a constant rate. Based upon thepatient anxiety, the speed or rate at which the elevator ascends ordescends may be controllably varied.

In keeping with the description of FIG. 3, once the initial exposurelevel or rate has been set, the illustrated embodiment thereaftermonitors the patient anxiety level (Step 102). Again, this step may beaccomplished by physical indicia observed by a therapist and entered bya computer operator into the system. Alternatively, it may beautomatically monitored by way of a sensor, as previously described. AtStep 105, the system makes a determination, based upon the patientanxiety level, as to whether to increase or decrease the exposure levelor rate. If the patient anxiety level is below a certain, predeterminedamount then the exposure intensity is increased at Step 106.Alternatively, the system proceeds to Step 107, which determines whetherto decrease the exposure level or rate. In this regard, if the patientanxiety level is above a certain, predetermined amount, the systemresponds by decreasing the exposure level or rate at Step 109.Otherwise, the exposure level or rate is maintained at a constant. Thiswill be the equivalent of maintaining the elevator at a constantascending rate or holding at a certain, prescribed floor, as previouslydescribed.

Although the illustrated embodiment describes reducing the exposurelevel or rate if the patient anxiety exceeds a certain level, this maynot always be desired. Indeed, in exposure therapy, the exposure levelis usually maintained even though the patient's anxiety level is high.The exposure is typically maintained until the patient anxiety begins tosubside, and then the exposure is increased. Terminating or reducingexposure while patient anxiety is high may adversely reinforce avoidanceor escape. The illustrated embodiment, nevertheless, recognizes that,consistent with the invention, the system may be designed with theflexibility to reduce exposure levels in extreme situations.

It will be appreciated that FIG. 3 illustrates the very broad elementsof the present invention, and is not dependent on any particularembodiment or virtual environment. Indeed, specific virtual environmentsand embodiments will be discussed in connection with FIGS. 4 through 16.

To better illustrate the present invention by discussing severalparticular embodiments, reference is now made to FIG. 4. FIG. 4illustrates the principal hardware components in an elevator embodiment,previously discussed, for use in treating patients having a fear ofheights. The system includes a computer 120 containing the virtualenvironment and for executing the software necessary for implementingthe virtual environment. An optional display 122 may also be provided.When included, the display 122 may be used by the therapist as a meansof viewing the same visual scene contemporaneously viewed by thepatient. That is, the video output by the computer 120 onto the displayscreen in the headgear worn by the patient, may be simultaneously outputto the display 122, where it may be viewed by the therapist 51.

Block 125 generically denotes the virtual reality equipment utilized bythe invention, including the headgear 20 (see FIG. 1), the sensor-glove30, and anxiety sensor previously discussed. Double-ended arrow 126represents bi-directional communication between the virtual realityequipment 125 and the computer 120. That is, information is communicatedfrom the computer 120 to the headgear, and information is communicatedfrom the sensor-glove and anxiety sensor to the computer 120.

In a preferred embodiment, an elevator platform 130 is provided. Theelevator emulated in the virtual environment is an open elevatordisposed within a central atrium area of a hotel. In this regard,reference is briefly made to FIGS. 8A-8D, which illustrate various viewsof this virtual environmental. Specifically, FIG. 8A illustrates a viewof the virtual environmental as taken looking outward from the elevator,while the elevator is positioned at ground level. It can be seen that onthe ground floor, the environment is depicted as having a plurality ofdining tables and an overhanging chandelier. FIG. 8B again illustratesthe virtual environment with the elevator positioned at ground level,and with the user looking upwardly. Similarly, FIGS. 8C and 8Dillustrate the same virtual environment, with the elevator at anelevated position and the user looking outwardly (FIG. 8C) anddownwardly (FIG. 8D). As can be seen, particularly in the downwardlydirected view of FIG. 8D, the elevator includes a platform 132 (see FIG.4) and a handrail 134. The hardware setup as illustrated in FIG. 4 hasbeen configured in connection with the virtual environment so that thephysical handrail 134 coincides with the virtual handrail illustrated inthe figures. When a user (e.g. patient) is wearing a sensor-glove 30,the system tracks the patient's hand movements so that when the handwearing the sensor-glove grasps the handrail 134, the image displayed inthe virtual environment illustrates the hand grasping the handrail.Similarly, the system tracks the movement of the hand in the vicinity ofthe handrail or elsewhere so as to coincide with the physicalpositioning of the user's hand. This provides an element of tactilefeedback to the user, particularly when grasping the handrail 134, tofurther enhance the sense of presence or immersion in the virtualenvironment and thereby enhance the effectiveness of the exposuretherapy.

To further enhance the tactile feedback, a motor 136 may be provided inconnection with the elevator platform 130. In this regard, the motor 136may be disposed to slightly elevate or, alternatively, vibrate theelevator platform 130 in conjunction with a simulated movement of theelevator within the virtual environment. This adds to the sense ofmovement visually apparent to the user by providing an emulated tactilemotion in connection therewith.

The double-ended arrow 140 shown in dashed line illustrates a connectionbetween the elevator platform 130 and the virtual reality equipment 125.This symbolic attachment is realized by a user standing on the platform130, and wearing the headgear and other virtual reality equipment 125.

Turning now to FIG. 5, a flowchart is provided to illustrate theoperation of a preferred embodiment of the virtual elevator environment.The system begins the therapy session by locating the elevator at groundlevel (Step 150). The visual environment as observed by the patient atthis level is illustrated in FIG. 8A. In one embodiment, the patient maycontrol the movement of the elevator by using a hand wearing thesensor-glove 30 to depress or activate imaginary control buttons in thevirtual elevator. Alternatively, the system may be configured to operateautomatically, utilizing anxiety sensors in connection with the elevatorcontrol. In this regard, the system may monitor anxiety sensors untilthe patient's anxiety level is low enough to begin elevating theelevator (Step 152). If, for example, the patient's pulse rate, bloodpressure or epidermal moisture level are below certain predeterminedamounts, the system begins emulating the elevation of the elevator (Step154). As the elevator continues upward, the anxiety sensors continue tomonitor the patient anxiety level. So long as the anxiety level remainsunder a certain acceptable level (Step 155), the system would continueto elevate the elevator (Step 156). Once, however, the patient anxietylevel exceeds a certain predetermined threshold, the system stops theelevator (Step 157). In the illustrated embodiment, Step 158 checks tosee whether the patient anxiety level begins to decrease after theelevator has been stopped. If so, control returns to Step 155 where thepatient anxiety level is again tested to determine whether to raise theelevator (Step 156) or maintain the elevator in its halted position(Step 157). If, however, halting the elevator in step 158 does notresult in decreased patient anxiety, the system may respond by loweringthe elevator (Step 160).

It will be appreciated that, in the foregoing example, the patientanxiety level may be sensed automatically, or may be manually input intothe system by the attending therapist. It will be further appreciatedthat FIG. 5 illustrates only one embodiment of the invention andvariations to the particular elevator control may be implementedentirely consistent with the concepts and teachings of the presentinvention. Indeed, further complexity may be added to the system toaccount for not only elevation changes in the elevator, but also ratechanges in the speed of the elevation or descent of the elevator. Inthis regard, reference is made to FIG. 6.

The embodiment illustrated in FIG. 6 also begins by locating theelevator at ground level (Step 170). Thereafter, it assesses thepatient's anxiety level either by therapist input or by automaticsensors, in a manner previously described (Step 171). If the patient'sanxiety is below a certain level, then the system begins elevating theelevator at a default rate (Step 172). Thereafter, the system monitorsthe patient anxiety level. If the anxiety level is acceptable (see Step175), the system may then check to determine the rate at which theanxiety level is changing. If the anxiety level is increasing toorapidly (see Steps 176 and 177), then the system will decrease the rateof elevation (Step 178). If the level of anxiety is increasing, but notincreasing too rapidly, then the system may maintain the presentelevator rate (Step 180).

If, however, the level of patient anxiety is not increasing (Step 176),then the system may operate to increase the rate at which the elevatoris ascending (Step 182). As can be verified from the flowchart, if, atStep 176, the system detects an increasing level of patient anxiety,then the system will either proceed through Step 178 or Step 180.Thereafter, system control returns to Step 175 wherein a check is madeto determine whether the level of patient anxiety is acceptable. If not,the system may stop the elevator (Step 185). Then, the system may check(Step 186) to determine whether the level of patient anxiety isdecreasing. If so, the system returns to Step 175, and once the level ofpatient anxiety is again acceptable, the system may begin increasing therate of elevation. If, however, at Step 186 the system does not detectdecreased patient anxiety, then the system may operate to lower theheight of the elevator (Step 187).

Again, it should be appreciated that the embodiment depicted in FIGS. 5and 6 are presented only for purposes of illustrating features of thepresent invention, and the broader aspects of the invention should notbe construed as limited to the embodiments illustrated in these figures.

As previously mentioned, the system may be configured to operate underthe control of either the patient, or a computer operator, rather thanunder the automatic control utilizing anxiety sensors. Under themanually operable scenario, the operation of the system may best bedescribed by reference to the state diagram illustrated in FIG. 7. Asillustrated in this figure, there are three states of operation: S0, S1,and S2. When in state S0, the elevator is moving upwardly. When in stateS1, the elevator is stopped, and, when in state S2, the elevator ismoving downwardly. The lines having arrows indicate a state change. Instandard state diagram notation, and as will be understood, associatedwith each arrow is an input and an output represented by notation iX/aY.In this notation iX represents an input, where X is a number from 0 to9. Similarly, aY represents an output, where Y is a numeral 0 to 9.Thus, there are 10 inputs and 10 outputs associated with the variousstate changes. Indeed, Table 1, produced immediately below provides allrequisite information for reading and interpreting the state diagram ofFIG. 7. The left-hand column of the table lists all states S0 throughS2, all inputs i0-i9 and all outputs a0 through a9. The right-handcolumn of the table provides the corresponding state, input, oroutput/action taken by the system.

                  TABLE I                                                         ______________________________________                                        S0              Elevator is moving up                                         S1               Elevator is stopped                                          S2               Elevator is moving down                                      i0               Elevator has not reached the top                             a0               Move elevator up (using desired speed)                       i1               Elevator has reached top                                     a1               Stop elevator moving up                                      i2               Up key/control button is pressed                             a2               Start moving elevator up                                     i3               Stop key/control button is pressed                           a3               Stop moving elevator up                                      i4               Down key/control button is pressed                           a4               Start moving elevator down                                   i5               Up key/control button is pressed                             a5               Start moving elevator up                                     i6               Elevator has reached bottom                                  a6               Stop moving elevator down                                    i7               Stop key/control button is pressed                           a7               Stop elevator moving down                                    i8               Down key/control button is pressed                           a8               Start moving elevator down                                   i9               Elevator has not reached bottom                              a9               Move elevator down (using desired speed)                     ______________________________________                                    

For example, when in state S0, the elevator is moving upwardly. Thereare two input conditions that can cause the elevator to transition fromstate S0 (where it is moving upwardly) to State S1 where it is stopped.One of these conditions occurs when the elevator reaches the top of itsrange of elevation. The second occurs when either the patient ortherapist manually controls the system to stop the elevator. The firstof these scenarios is represented by i1 (where the elevator has reachedthe top). The corresponding output a1 instructs the system to stop theelevator from moving upwardly. Similarly, i3 represents the depressionof the manual control to stop the elevator from moving upwardly.Corresponding output a3, likewise, stops the elevator from movingupwardly.

In addition to the manipulation of the visual virtual environment asdiscussed above, the invention may also be configured to provide audiblefeedback to the user by way of speakers 24. In this regard, the audiblefeedback may not only provide a sound consistent with the motorizedsound or hum of an elevator (that may vary in connection with thevarying rate or movement of the elevator), but also may provideadditional, environmental noise as well. For example, when the elevatoris located at ground level and the visual display is depicting an atriumarea of a hotel, it may also be desired to emit the sound of a pluralityof personal conversations, for example, emulating the presence of peoplein the atrium area. This sound may be attenuated as the elevator risesabove the atrium level, consistent with sound attenuation in such areal-world scenario.

In addition to the elevator embodiments described above, otherembodiments or graphical environments may be provided for treatingpatients with a fear of heights. One such embodiment is shown in FIG. 9and includes a view from a balcony. As can be seen in FIG. 9, a balconyhandrail is provided like that discussed in connection with the elevatorhandrail of FIGS. 4 and 8A through 8D. Indeed, the same platformconstructed for the elevator embodiment may be utilized in connectionwith the balcony embodiment. Preferably, a plurality of balcony scenesare provided, each of a varying height. That is, one balcony embodimentmay emulate the view from a second or third floor balcony. During aninitial treatment session, a patient may be exposed to this environment.Once patient anxiety levels have decreased by virtue of this exposure,the patient may then be exposed to additional balcony scenes ofincreasing intensity (i.e., higher floors).

Yet another embodiment is illustrated in FIG. 10, wherein the virtualenvironment positions a patient on a suspended, walking bridge spanninga ravine. Depending upon the level of patient anxiety, the system may beadapted to increase the elevation of the suspended bridge or,alternatively, vary the stability of the bridge. In this regard, thesystem may be configured to provide swaying or other turbulence to asuspended bridge. In such an embodiment, it would be desirable toprovide tactile feedback, similar to the elevator handrail, to reinforcethe sense of presence or immersion experienced by the patient.

In addition to utilizing various embodiments of the present invention toprovide exposure treatment to patients suffering from acrophobia, theinvention is not so limited. Indeed, it is contemplated the inventioncan be utilized to treat patients having a wide variety of anxietydisorders. The fear of flying is another such example. To be sure, inone embodiment the present invention has been adapted to emulate theinterior of a passenger aircraft, from the vantage point of a passengerseat positioned next to a window. Using the headgear, the patient hasthe freedom and flexibility to observe the virtual surroundings withinthe aircraft cabin, as well as view a virtual environment outside theaircraft by looking through the window. Like the hardware setupillustrated in FIG. 4, FIG. 11 depicts a similar hardware setup for thisembodiment of the present invention. Again, a computer 200 and optionalcomputer monitor 204 are provided to generate and simulate the virtualenvironment. Virtual reality equipment 205, including the headgear,sensor-glove and anxiety sensor are also provided. Rather than theelevator platform illustrated in FIG. 4, a chair is provided for thepatient to sit in. Preferably, this chair closely conforms in size andshape to a typical aircraft seat, to tactily emulate the virtualenvironment. A plurality of motors 215, responsive to the computer 200,may be provided to further enhance the environment by moving the seat210. In this regard, a mechanism, such as a motor, may be disposed totilt the seat forwardly or rearwardly coincident with aircraft landingsand takeoffs. Similarly, a mechanism may be provided to tilt the seatfrom side to side to better emulate turns or aircraft banking. Finally,a mechanism may be provided to generate seat vibrations to betterenhance the sense of movement by the patient seated in the chair 210.

Before proceeding with the description of a preferred software flowchartand state diagram, reference is first made to FIGS. 14 through 16. FIG.14 illustrates a view of the interior aircraft cabin space as viewed bythe patient, seated in a passenger seat. While the aircraft of thisembodiment is empty, it may be desired to add the presence of otherpassengers, flight attendants, etc. to better enhance the sense ofpresence within the virtual environment. Similarly, correspondingsurrounding noise (e.g., conversations) may be emitted via headsetspeakers 24 to further enhance this embodiment. Likewise, aircraft noiseis desirably emitted over the speaker. The noise is controlled tointensify in volume in connection with aircraft takeoff, for example,and a lower volume is emitted coincident with aircraft taxiing.

FIG. 15 illustrates a view of an airport, as observed by looking throughthe aircraft window. It will be appreciated that the aircraft isairborne when observing the view as illustrated by FIG. 15. Similarly,FIG. 16 illustrates an alternative view out the passenger window, andover an aircraft wing. This view illustrates movement of the aircraft bydepicting the ground as blurred in relation to the aircraft wing.

In a presently preferred embodiment, prerecorded video images may beused to provide the view of the exterior of the plane seen through theaircraft window. This allows a high sense of presence to be createdwhile only requiring simulation of the virtual environment of theaircraft interior. This reduces the computational requirements of thesystem to a level allowing the software to be run on a personalcomputer, resulting in an enhancement of system performance and asignificant cost reduction over the mainframe system which wouldotherwise be required to generate a three-dimensional simulation of theexterior scenery. Running the simulation on a personal computer basedsystem also allows private clinicians and therapist to operate thesystem directly, without requiring the aid of computer operationspersonnel, thereby providing more immediate control of the simulation inresponse to patient anxiety levels. In an alternative embodiment, theinterior of the aircraft may also be simulated by the presentation ofprerecorded images of the interior of a real aircraft in a mannerresponsive to the patient's head position and orientation.

The video images may be played directly from storage on a hard-drive,CDROM, or by streaming over a network, the Internet or othercommunications system to facilitate remote treatment. Furthermore, thevideo images may also be encoded in any standard video format, includingsuch examples as MPEG, MPEG2, Quicktime or AVI. The video images may berecorded at a higher resolution than would be possible for a computergenerated simulation, and may in fact include recorded images from areal flight, thereby significantly enhancing the realism of the virtualexperience. Since the view out of the window includes only objects at amuch greater distance from the patient than the interior of the plane,the loss of parallax resulting from displaying a prerecorded video imagerather that actually simulating the exterior scenery is negligible.

Another way to significantly improve the realism of the images andincrease the sense of presence is to add jitter to the images,simulating the turbulence and small shocks which commonly occur as anaircraft moves on the ground or encounters turbulence in flight. In thepreferred embodiment, this jitter may be provided cheaply and with useof little computation power by randomly causing slight changes in thehead position coordinates of the patients head in the virtual realitysystem computations.

It is also possible to replay short looping video streams to simulatecontinuous conditions such as sitting at the gate or in flightconditions, however it is necessary to include longer video segments tosimulate taxiing, take off, landing, and weather transitions. In orderto enhance the realism of the experience and increase the presenceproduced by the virtual reality technology, the transitions between thevarious video segments which can constitute the external scenery duringa therapy session must be as smooth as possible. This smoothness oftransition can be accomplished by limiting the transitions to certainset points during the video sequences and by transitioning to a smoothlyintegrated scene at a predetermined point during the next replay of oneof the short repeating loops. The longer sequences will generally onlyrun once, and will automatically transition into the next phase of thesimulation.

During the longer video sequences, it may be desirable to include anindicator to inform the therapist whether it is possible to transitionto the next sequence at a given time. In the presently preferredembodiment this is indicated by inclusion of an indicator pixel on themonitor view screen. When it is possible to transition, the indicatorpixel is illuminated. This pixel need not be present in the virtualenvironment. Furthermore, it should be obvious that a number of otherindicating means are possible.

Referring now to FIG. 12, a top-level description of the softwareoperation for this embodiment is depicted and FIG. 13, which shows astate diagram illustrating the various states, and state transitions ofthe above-described embodiment. Preferably, a therapy session beginswith the aircraft at state 300 sitting at the gate of an airport inpreparation for departure with the engines off. During this phase of thesimulated flight, a short video loop simulating the exterior scenery isplayed. Accompanying sound files including low level background noiseand music are played in conjunction with the repeating video sequence.Upon command by the therapist or patient, or input from the anxietysensors the system transitions to the next state 302, simulating sittingat the gate of an airport in preparation for departure with the engineson by simply activating a sound file simulating the engine noise. Thisstate may be maintained until the therapist commands transition to thenext state or, alternatively may be maintained for a predetermined timebefore automatically transitioning to the next state.

The next state 304 is that of taxiing from the terminal to the runway(Step 250). During this phase of the flight, a longer video sequencesimulating the external scenery as the plane moves from the gate isfirst displayed, followed by entry into state 306, which includes alooping video sequence in which the aircraft circles about the runway.When the aircraft has taxied for a sufficient time, the therapist cancause the exterior scenery to transition to state 308 wherein a shortrepeating video sequence is displayed simulating a stationary scene asthe plane sits at the runway in preparation of takeoff. These videosequence are accompanied by sound files including both stationary andmoving engine noise along with a low level of background noise.

Not only is this an effective way of gradually introducing the patientinto the feared, airborne environment, but also presents a morerealistic approach to exposure therapy, since preflight taxiing isalways a part of the flight experience. During the taxiing, thepatient's anxiety level may be monitored to determine whether theexposure of the therapy session should be taken to the next level (Step252). If the patient's anxiety level exceeds a predetermined thresholdlevel, then the illustrated embodiment stops the taxiing (Step 253),until the patient's anxiety returns to an acceptable level. If, however,the patient's anxiety level is below a predetermined threshold level,then the virtual emulation continues with the preflight process. Thatis, if the plane has not yet reached the runway, it continues to taxi(Step 254). If, however, the plane has reached the runway, then theaircraft proceeds to the runway in preparation for take off (Step 255).

When the therapist signals the system to proceed with takeoff, the videosequence transitions to state 310, wherein a longer video sequence isdisplayed of the external scenery during takeoff and the initial portionof an ascent. During the takeoff, audio files are played including the aspeech by the stewardess concerning in flight safety procedures, thedistinctive "chime" heard as a plane prepares for takeoff. Thesimulation also includes an audio file producing the distinct change inengine noise associated with a typical flight takeoff and thedistinctive sound produced by retraction of a plane's landing gear.Motors 215, or alternatively a sub-woofer speaker, may be controlled toincrease the seat vibrations, and the virtual environment, as viewedthrough the passenger window, illustrates the acceleration and increasedvelocity of the aircraft proceeding down the runway. Once an appropriatevelocity has been reached, the system operates to tilt the seatrearwardly and control the environment out the passenger window toreflect increased aircraft altitude. It will be appreciated that duringthis time the system continues to monitor the patient anxiety, and ifthe patient anxiety exceeds a predetermined threshold, the system mayabort the simulation.

Preferably, however, the takeoff proceeding will continue until theplane reaches a certain prescribed altitude. Once the cruising altitudehas been reached, the system transitions to state 312 initiating a shortvideo sequence simulating clouds passing by the exterior of the planeduring a steady flight under good conditions and associated audio filesincluding the steady sound of in flight engines. The system continues tomonitor patient anxiety (Step 260). With increased levels of patientanxiety, the system may respond by simulating very smooth flightconditions. In this regard, the speaker emits a fairly constant hum tocorrespond to smoothly running engines, and a very gentle, regularvibration is provided by the motors 215 to the seat 210.

With reduced levels of patient anxiety, however, the system ispreferably adapted to simulate rougher flights. When a rougher flighthas been selected, the external scenery sequence smoothly enterstransition state 314. State 314 includes a short video sequencesimulating passage through a cloud bank and thereby providing a smoothtransition from the repeating good weather loop to another short loopingsequence presenting a view of darker storm clouds displayed during thebad weather state 316. The audio files associated with the rough flightsequence include the in flight engines, a bell chime indicating the needto fasten seat belts, the crack of lightning and the rumble of thunder.

Additionally, the amount of apparent jitter of the system is increasedduring the rough flight sequence by increasing the random perturbationsto the patient's head coordinates as previously described. Motors 215may also be controlled to deliver sudden jolts to the seat 210 withcorresponding perturbations reflected in the video display. The speakersmay also be controllably varied to emit sound variations coincident withthese disruptions, to simulate the aircraft hitting air pockets orencountering turbulence.

When the therapist determines that the rough weather state 316 has beenmaintained for a long enough time, a second transition state 318 may beinitiated, again displaying video sequence depicting a transitorypassage through a cloud bank followed by a smooth transition back to thegood weather state 312.

When the therapist determines that the flight simulation has proceededfor a sufficient length of time, he or she may activate the system toinitiate the landing sequence. The landing sequence includes two longervideo sequences including an approach sequence as the plane nears theairport and an actual landing sequence. State 320, the approach sequencestate includes a view as the plane passes by a city while descending andapproaching the airport, and is associated with audio files includingthe sounds of the seat belt warning chime and the characteristic thumpassociated with deployment of the landing gear of an aircraft. Fromstate 320, the system may transition back into state 312 to simulate amissed landing approach or low altitude pass over the airport (buzzingflight) or may proceed to state 322.

State 322, the landing sequence provides an external view of the sceneryas the plane actually proceeds through final approach and landing andincludes audio files simulating the thump of landing, tire skids and thecharacteristic engine noises associated with thrust reversal andbreaking of an aircraft. Of note, significant jitter may be added tosimulate the bumps and shocks associated with the initial contact of theaircraft with the surface of the runway.

Following the landing sequence, a short repeating video loop is entereddisplaying the external scenery while the plane is in state 324, at restat the end of the runway. From here the therapist may choose to end thesimulation, or may select transition to state 326, including a videosequence simulating taxiing back to the takeoff position and may restartthe takeoff sequence to simulate another flight. It should be notedthat, in addition to stopping the simulation after a successful landingsequence, the therapist may abort the simulation at any point during thetherapy session. Furthermore, in automatic mode the simulation may beautomatically terminated if at any time the patient anxiety levelexceeds a predetermined threshold.

It should be recognized that in variations of the above presentlypreferred embodiment that simulation may be controlled by the therapist,the patient or automatically by the use of anxiety sensors. Furthermore,the capability exists for therapist based control of the simulation froma remote location utilizing a network, Internet or modem connection. Insuch a remote therapist controlled embodiment it is also necessary thatinformation about the patient's level of anxiety, either as detected bya sensor or verbally described by a patient, be relayed to thetherapist.

In addition to those embodiments depicted in the drawings and previouslydescribed, it will be appreciated that the present invention may beutilized in connection with the treatment of other anxiety disorders aswell. For example, the present invention may be used in connection withthe treatment of patients suffering from post-traumatic stress disorder.It is well documented that many U.S. military veterans, who have servedin combat, suffer from post-traumatic stress disorder (or PTSD).Accordingly, exposure therapy by way of virtual environments may beutilized in the treatment of such patients. Clinical reports haveindicated that often the highest levels of anxiety of post-traumaticstress disorder patients are exhibited in connection with the memory ofbeing transported by helicopter into combat. Often these memories andthe associated anxiety are triggered merely by the sound of a helicopterflying overhead. Therefore, a virtual environment adapted to treatpost-traumatic disorder patients may be created to emulate the followingscenario. Initially, merely the sound of a distant helicopter is emittedover a speaker. This sound may grow in intensity and volume, so long asthe patient maintains safe and appropriate levels of anxiety. As thesound is controlled to intensify, a visual image of the helicopter,first small and then growing in size, may be displayed on the displayscreen before the patient.

The environment is further controlled to emulate the approach of thehelicopter, which is controlled to land in front of the patient. Thepatient then boards the helicopter which is controlled to take off andfly over jungle terrain, emulating that of Vietnamese combat territoryincluding muzzle flashes and simulations of tracer bullet fire, forexample, or any other appropriate territory for a given patient. Duringthis time, the sound of the rotary helicopter blades are audiblethroughout the emulation, and the patient may be seated in a seatconfigured to vibrate much like that discussed in connection with theprevious, flight embodiment. Other auditory stimuli which presentedduring the simulation include battle sounds such as guns firing,missiles firing, explosions, radio chatter, and people yelling andscreaming.

If, at any time, the patient anxiety level exceeds a predeterminedlevel, the virtual environment is configured and controlled to respondaccordingly. For example, if a patient exhibits undue anxiety as thehelicopter is making its initial approach to the patient, the system maymerely control the helicopter to fly off in another direction. Once thepatient's anxiety subsides, another helicopter may then be brought intothe environment to approach the patient.

Embodiments of the present invention have also been identified for usein treating other PTSD sufferers. In such embodiments, the sufferers maybe exposed to a virtual environment that closely emulates theenvironment in which their trauma occurred (e.g., driving for motorvehicle accident survivors, assailant for rape survivors, etc.).Similarly, variants of the present invention may be utilized in patientssuffering from obsessive-compulsive disorder, by exposing them toenvironments that would otherwise trigger compulsive urges.

It will be appreciated that the particular embodiment or environment maypreferably be tailored to specific patient needs. It will be furtherappreciated that the treatment methods discussed herein are much moreefficient and cost effective for treating patients than actual exposuremethods. That is, in connection with patients having a fear of flying,the emulated aircraft environment is much more cost effective thanactually having to purchase aircraft tickets or flight time from aprivate charter. In addition, staying within the confines of thetherapist's office, patient confidentiality is maintained. Moreover,potential patient embarrassment by having anxiety attacks in a publicplace are eliminated. Furthermore, unlike a real scenario, if it isclinically warranted, the exposure session may be immediatelyterminated. It is well appreciated that such an option is not availablein a real-world exposure session.

The foregoing description has been presented for purposes ofillustration and description. It is not intended to be exhaustive or tolimit the invention to the precise forms disclosed. Obviousmodifications or variations are possible in light of the aboveteachings. The embodiment or embodiments discussed were chosen anddescribed to provide the best illustration of the principles of theinvention and its practical application to thereby enable one ofordinary skill in the art to utilize the invention in variousembodiments and with various modifications as are suited to theparticular use contemplated. All such modifications and variations arewithin the scope of the invention as determined by the appended claimswhen interpreted in accordance with the breadth to which they are fairlyand legally entitled.

What is claimed is:
 1. A virtual reality system for treating patientshaving a fear of flying, said system comprising:a display for displayinga graphical environment emulating the interior of an airplane, saidgraphical environment including a window; a storage device for storing aplurality of prerecorded video sequences, said prerecorded videosequences being representative of standardized environmental scenarioscorresponding to views through an airplane window during differentphases of the flight of an airplane; a head position sensor fordetecting the position of a patients head and generating positionsignals corresponding to the position of the patient's head; and acomputer responsive to said position signals for controlling the displayof the graphical environment by the display in response to said positionsignal; wherein said computer may retrieve one of said prerecorded videosequences and present said prerecorded video sequence within said windowof said graphical environment to simulate a view through said windowduring said particular phase of flight.
 2. The virtual reality system ofclaim 1, wherein said prerecorded video sequence includes images ofscenery recorded through the window of a real aircraft during aparticular state.
 3. The virtual reality system of claim 1, wherein saidprerecorded video sequence is repeated to simulate a continuous statethereby allowing simulation of particular phase of flight for anindefinite period of time.
 4. The virtual reality system of claim 3,wherein a smooth transition to a second particular simulated phase offlight is accomplished by replacing said repeating prerecorded videosequence with a second prerecorded video sequence displaying the viewduring the second particular phase of flight at a specific time duringsaid repeating prerecorded video sequence.
 5. The virtual reality systemof claim 2, further including an indicator for indicating to a therapistwhen it is possible to transition from a first prerecorded videosequence to a second prerecorded video sequence.
 6. The virtual realitysystem of claim 1, further comprising a speaker for delivering sound,the sound being logically related to the graphical environment.
 7. Thevirtual reality system of claim 6, further comprising a prerecordedaudio sequence which is played through said speaker in conjunction withsaid prerecorded video sequence.
 8. The virtual reality system of claim2, wherein jitter is induced into said graphical environment inconjunction to pre-selected events during said prerecorded videosequence.
 9. The virtual reality system of claim 8, wherein said jitteris induced by varying the head position coordinates processed by saidcomputer.
 10. The virtual reality system of claim 8, wherein said jitteris induced during the particular state by randomly varying the headposition coordinates processed by said computer.
 11. The virtual realitysystem of claim 6, wherein said speaker includes a sub-woofer mountedunder a chair.
 12. The virtual reality system of claim 1, wherein saidpre-recorded video sequence is adapted such that a portion of the videosequence provides a smooth transition to a portion of a secondpre-recorded video sequence.
 13. A computer program embodied on acomputer readable medium for treating patients with fear of flyingcomprising:a means for receiving data detailing the position of a bodyportion of a patient; a means for storing a prerecorded video sequencerepresentative of scenery which would be visible from an aircraftwindow; and a means for generating a simulated graphical environmentresponsive to the data detailing the position of a body portion of apatient, said simulated graphical environment including:a threedimensionally rendered view of the interior of an aircraft, said threedimensionally rendered view including a window; and wherein saidprerecorded video sequence may be presented within said window of saidthree dimensionally rendered view to simulate the view through anaircraft window; and a means for outputting data encoding the generatedsimulation of a graphical environment to a display for presentation tothe patient.
 14. The computer program embodied on a computer readablemedium for treating patients with fear of flying of claim 13, furthercomprising a means for altering the data detailing the position of abody portion of a patient to introduce apparent jitter into thegenerated simulation of a graphical environment.
 15. The computerprogram embodied on a computer readable medium for treating patientswith fear of flying of claim 14, wherein said jitter is randomlygenerated.
 16. The computer program embodied on a computer readablemedium for treating patients with fear of flying of claim 14, whereinsaid jitter is generated to correspond with specific events in thesimulation.
 17. The computer program embodied on a computer readablemedium for treating patients with fear of flying of claim 13, whereinsaid prerecorded video sequence includes a video sequence from an actualflight.
 18. The computer program embodied on a computer readable mediumfor treating patients with fear of flying of claim 17, wherein saidprerecorded video sequence is adapted such that a portion of theprerecorded video sequence provides a smooth transition to a portion ofanother video sequence.